The invention concerns a composite plate for the facing of building surfaces, and in particular relates to facades having light weight structures, with a core layer extending between two cover sheets. A decorative panel, in particular a natural stone panel, is adhesively bonded to the outward facing surface of one of the two cover sheets.
Composite plates having a decorative panel of marble and a core layer with a metallic honeycomb structure are known from U.S. Pat. No. 3,723,233. Due to their light weight and high dimensional stability, such plates are increasingly being used for the external and internal facing of buildings, halls, railroad and subway stations, baths, swimming pools, and internal installations, in particular on ships. However, the known composite plates in the form of light weight natural stone panels only satisfy the pertinent national fire specifications under certain limited conditions. In particular, the known composite plates do not satisfy the requirements of the more stringent fire testing procedures for facing plates according to DIN (German Industry Standard) 4102 B1.
This is also true for the composite plates known from U.S. Pat. No. 4,299,872 and U.S. Pat. No. 4,598,007, in spite of the application of certain fire protection measures, such as the use of nonflammable adhesives (U.S. Pat. No. 4,598,007) or the filling of the honeycomb layer with material which foams in the event of fire or in response to the effect of heat (U.S. Pat. No. 4,299,872).
These references do not mention the use of plates for the facing of buildings, where the decisive factor is neither the protection against heat nor the light weight of the plate, but rather the cohesion of the plates in the event of fire. In buildings, the falling parts of the plates would endanger persons, in particular fire fighters employed in controlling the fire. The composite plates mentioned in French Patent Publication No. 2,239,573 are again not designed for the outside facing of the buildings. Furthermore, this reference proposes the use of asbestos, which in view of its harmful effects on health, is no longer used.